Topical deodorant formulations for use in controlling odour in the underarm area have been available in the market for many years, containing deodorizing active ingredients that generally work by inhibiting bacterial growth, masking odours, or by chemically fixing undesirable odours. One significant challenge with deodorant formulations has been to obtain longer lasting effect. Many formulations work well immediately following application or for a few hours afterward. However, as time passes following application, many formulations have not been able to offer sustained protection against odour. Because users typically apply deodorants after bathing in the morning, and may not have the opportunity to reapply until the next morning, it is desirable to have a deodorant which can provide odour control for a full 24 hours following application.
The longevity of deodorant effect, while important, is not the only feature that is needed in a commercially acceptable deodorant formulation. For deodorants which will be made into solid stick forms for use by the consumer, stability and shelf life is also important. Deodorant sticks, over time, tend to suffer weight loss due to the condensing out of moisture from the stick. Moisture typically rises to the surface of the solid. The moisture can then evaporate, which results in a shrunken, hardened product that pulls away from the container wall, or the moisture may stay on the surface of the deodorant stick, which may result in a product with a mushy, moisture-logged surface. In either case, the result is product which spoils over periods of storage. Manufacturers must therefore specify relatively early “best-before” dates on the products to reduce the risk that a consumer purchases a product past its prime. Expired deodorants must also be replaced with new stock. It would be advantageous to have a deodorant formulation which is stable for a longer time following manufacture, so that the resulting products may be stored and salable for longer.
In addition to the above issues, consumers are becoming ever more conscious of the ingredients in their personal care products. There is increasing demand for products which have been formulated with natural ingredients which are not synthetically derived, and which can be formulated with minimal environmental impact. Many consumers are also cautious of ingredients used in deodorants that have been shown to be carcinogens, such as triclosan, or ingredients that are petroleum-derived, such as propylene glycol.
The need for naturally formulated deodorant products with good efficacy which can be sustained for longer periods of time, combined with the better stability and shelf-life required for a commercial product, has posed challenges to manufacturers. There are some such deodorant formulations available which claim efficacy over 24 hours, but the stability of these formulations has been compromised. Chemists in this field have found that it is much more difficult to formulate efficacious and stable deodorants when one is limited to using natural ingredients.
What is needed is a solid stick deodorant formulation, that preferably contains all natural or naturally sourced ingredients, which shows efficacy for a longer time following application, and is also stable for a longer time once formed into a deodorant stick product.